This invention pertains to an apparatus for applying an aqueous silicone emulsion to a paper web as the web is moving through a printing press.
Silicone applicators are used in newspaper, business forms and commercial web operations in order to lubricate the surface of the web for ease of handling and separation of the sheets. The silicone concentrate is mixed with water in a mixing tank and then pumped to a tray from which it is picked up by rollers and applied to the web. Heretofore, the pressman has had to manually mix up a batch of the emulsion in a large mixing tank on the press room floor, and the usual method of delivering the emulsion from the tank on the floor to the elevated roller trays has been by means of a heavy rotary vane pumps. With this type of system, there was little control over the silicone emulsion concentration, and it required the pressman to constantly monitor the silicone reservoir to assure continuous delivery of silicone emulsion to the web.
The present invention is intended to automate the silicone application apparatus permitting the automatic mixing of small quantities of the silicone emulsion at a time so that the concentration of silicone can be controlled and easily altered. The mixing tank is small enough to be located up from the floor of the press room in close proximity to the elevated roller trays. The silicone emulsion is delivered to the mixing tank from supply drums with means for switching from one drum to the other when the drum is empty. The system eliminates the heavy rotary vane pump and filters which were heretofore necessary in order to lift the emulsion from the floor level, and it provides complete control over the application by the pressman.
In accordance with one embodiment of the invention, the silicone applicator comprises at least one silicone concentrate supply tank, a water supply means containing a supply of water and a mixing tank for batch mixing the silicone concentrate with the water to form an aqueous silicone emulsion of the desired concentration. The water supply means may be conveniently a water line controlled by means of a solenoid valve.
The applicator also has a silicone holding tray for holding a supply of silicone emulsion, and roller means rotating at least partially in the holding tray picks up the silicone emulsion from the holding tray and applies it to the paper web. There is a first transfer means for transferring to the mixing tank metered quantities of the silicone concentrate from the supply tank and water from the water supply means. This first transfer means preferably includes a water transfer means such as the aforementioned solenoid valve which controls the transfer of water to the mixing tank in sufficient quantity to fill the mixing tank to a predetermined level. The first transfer means has a silicone transfer means for repeatedly transferring metered or measured charges of silicone concentrate to the mixing tank from the silicone concentrate supply tank.
The applicator also includes an adjustable control means for controlling the amount of silicone concentrate transferred by the first transfer means to the mixing tank so that the concentration of the aqueous silicone emulsion mixed in the mixing tank may be controlled. This adjustable control means preferrably controls the number of measured charges of silicone concentrate delivered to the mixing tank for each filling of the tank by the water transfer means. If desired, there may also be means for adjusting the amount of emulsion in each charge delivered to the mixing tank. There is further included a second transfer means for delivering the mixed silicone emulsion from the mixing tank to the holding tray and it is desired that there also be a means for recirculating the emulsion from the holding tray back to the mixing tank.